Regulation of temp

Question 1

How do we regulate body temp, and according to what?

Answer 1

By blood flow, adjusting to external temp
- core stays 37 degree

Question 2

What are some behavioral responses to cold?

Answer 2

Warmth seeking posture, nesting, huddling, burrowing, and clothes

Question 3

What are some behavioral responses to heat?

Answer 3

Cold seeking posture, no need for solid nests or huddling and aircodition

Question 4

What are the physiological response to cold?

Answer 4

Redistribution of blood flow from skin to abdominal viscera:
- skin vasocontriction

also:
- piloerection (goose bumps)
- muscle shivering
- brown fat

Question 5

What are the physiological response to heat?

Answer 5

Redistribution of blood flow from abdominal viscera to skin:
- skin vasodilators

also:
- sweating

Question 6

Describe the central regulation of body temp.

Answer 6

Temp. sensitive neurons in the preoptic area in the hypothalamus receives input from temp sensitive fibers in periphery (e.g. shivering, brown fat), and responds to local changes in brain temp

Question 7

What else can affect the POA?

Answer 7

Infection –> immune response –> pyrogenic mediator ==> fever
Also hormones

Question 8

Describe cold sensitive fibers.

Answer 8

Max firing: 30-20 degree
Inactivated by heat
Active at thermal comfort state
Adaptation possible

Question 9

Describe warm sensitive fibers.

Answer 9

Max firing: 40-43 degree
Inactivated by cold
Active at thermal comfort state
Adaptation possible

Question 10

Describe noxious cold fibers.

Answer 10

Activated at 20-10 degree
Increased firing down to 0 degree
Inactive at thermal comfort state
Adaptation not possible

Question 11

Describe noxious heat fibers.

Answer 11

Activated above 43 degree
Peak discharge at 45-53 degree
Inactive at thermal comfort state
Adaptation not possible

Question 12

What channels are responsible for sensing temp?

Answer 12

TRP channels
E.g., TRPM8: cold + menthol, TRPV1: noxious warm + capsaicin, TRPV3: warm, TRPM1: noxious cold

Question 13

Why are children less cold than adults?

Answer 13

More brown fat

Question 14

How are brown fat activated?

Answer 14

Cold fiber in skin –> POA –> neural activation of BF

Question 15

Describe how BF generate heat.

Answer 15

Burns fat to generate heat:
NE binds to beta-AR –> ATP conversion to cAMP –> PKA activation by cAMP –> HSL –> lipids are converted to FFA –> mitochondria generated heat

Question 16

How are BF associated with metabolic health?

Answer 16

People with brown fat have less risk of developing type II diabetes

Question 17

What health benefits does winterswimming seem to have?

Answer 17

• lower levels of cortisol during night (less stress)
• better glucose tolerance (but not more BF)
• more heat production by the neck
• higher energy consumption during cooling